1. Field of the Invention
The present invention relates to a method for manufacturing a cup of a cup biopsy forceps for an endoscope, which is inserted in a forceps channel of an endoscope to remove a specimen of tissue from a living body cavity for the purpose of diagnosis.
2. Description of the Related Art
In general, a cup biopsy forceps for an endoscope is provided with a pair of forceps cups in the form of spoons at a front end of a sheath thereof which is inserted in and removed from a forceps channel of an endoscope. The forceps cups are opened and closed, by pulling or extending an operation wire which extends within the sheath in the axial direction thereof, so that mucous membrane tissue can be bitten off and removed by cutting edges formed at the edges of the forceps cups.
In the past, the forceps cup has been formed by cutting a metal rod. However, the manufacturing cost is remarkably high, and hence, recently, forceps cups have been formed by pressing a plate (e.g., Japanese Unexamined Patent Publication No. 9-276285 and No. 10-24045).
In a known manufacturing method of an endoscopic biopsy forceps cup, a metal plate is punched along a contour of a cup blank, and the cup blank thus obtained is subject to a drawing operation using a press to produce a predetermined forceps cup.
When the flat metal plate is subject to the drawing operation using a press to obtain a predetermined shape of a forceps cup (substantially in the form of a spoon), the metal plate is entirely drawn toward the drawing portion. However, if the drawing resistance is not identical in all the directions, the amount of drawing is irregular.
Consequently, if the forceps cup blank which has been obtained by punching the metal plate along the contour of the forceps cup is subject to the drawing operation, the amount of drawing is not uniform in all directions. Thus, precise forceps cup cannot be produced, leading to a reduced cutting efficiency of the forceps cups.
It is an object of the present invention to provide a method for manufacturing a biopsy forceps cup for an endoscope which can be precisely formed by pressing a metal plate.
To achieve the object mentioned above, according to the present invention, a method is provided for manufacturing a biopsy forceps cup for an endoscope in which a spoon-shaped forceps cup is formed by drawing a metal plate blank by a press, the method including forming a first cut on the metal plate blank, wherein the first cut surrounds a contour of a portion of the metal plate blank defining a forceps cup blank corresponding to the forceps cup, the first cut being discontinued by a plurality of first connection portions; forming a second cut on the metal plate blank, wherein the second cut surrounds the first cut, the second cut being discontinued by a plurality of second connection portions; and carrying out a drawing operation on the metal plate blank while each of the first and second connection portions remain connected with respective neighboring portions defined by each respective the first and second cuts.
In an embodiment, the first connection portions are spaced from one another at a substantially equal distance, and the second connection portions are spaced from one another and are spaced from the first connection portions at a substantially equal distance.
In an embodiment, three connection portions constitute each of the first and second connection portions.
In an embodiment, one of the first connection portions is located at an end of the forceps cup blank in a longitudinal direction thereof, and wherein remaining two connection portions of the first connection portions are located at both ends of the forceps cup blank in a lateral direction thereof, perpendicular to the longitudinal direction.
In an embodiment, the first cut is provided with two first connection portions at both ends of the forceps cup blank in a longitudinal direction thereof, and the second cut is provided with two second connection portions at both ends of the forceps cup blank in a lateral direction thereof, perpendicular to the longitudinal direction.
In an embodiment, the first cut is provided with two first connection portions at both ends of the forceps cup blank in the lateral direction thereof, and the second cut is provided with two second connection portions at both ends of the forceps cup blank in a longitudinal direction thereof, perpendicular to the lateral direction.
Preferably, the second cut is provided spaced from the first cut at a constant distance around the first cut.
The first and second cuts can be formed by a press, or by laser cutting.
In an embodiment, after the drawing operation is completed, a piercing operation is carried out.
In an embodiment, after the piercing operation is completed, the first and second connection portions are cut, so that the forceps cup can be removed from the blank plate.
In an embodiment, the blank plate is placed on a female die whose contour corresponds to a cutting line of the forceps cup. A male die, whose contour corresponds to the female die, is pressed into the female die by a press to cut the forceps cup from the blank plate.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 11-278079 (filed on Sept. 30, 1999) which is expressly incorporated herein by reference in its entirety.